Impactos das mudanças do uso e cobertura da terra na hidrologia de uma bacia de clima semiárido: o estudo de caso da bacia hidrográfica do Rio Taperoá (PB)

Abstract

Changes in land use and land cover have impacts on hydrological processes and their combined effects affect water resources. Therefore, understanding the mechanisms between land use and land cover and hydrology is essential to improve water and soil management. In this sense, the objective of this research was to evaluate the impacts of changes in land use and land cover on the hydrological behavior of the Taperoá River basin under different scenarios using the Soil and Water Assessment Tool (SWAT) model. In this work, climate data for the period from 1994 to 2018 were used, in addition to maps of soil types, land use and land cover and a digital elevation model. The model was calibrated in order to obtain better adjustments for the modeling, using 12 parameters. To evaluate the impacts of changes in land use and land cover, four scenarios were developed: C1 and C2 – conversion of forest to pasture of 20 and 50%, respectively; and C3 and C4 – pasture-to-forest conversion of 20 and 50%, respectively. The results showed that, in general, the deforestation scenarios presented an increase in the average flow of 0.01 and 0.03 m³/s for C1 and C2, while in the reforestation scenarios there was a decrease in the flow of 0.01 and 0.03 m³/s for C3 and C4, respectively. The increase in native forest provided a decrease in surface runoff of 0.07 (C1) and 0.17 mm (C2). Regarding pasture expansion, the results showed an increase in surface runoff of 0.11 and 0.27 mm in C3 and C4, respectively. Therefore, reforestation scenarios have a positive impact on the region, as they increase the contribution of groundwater and reduce peak flows, improving the basin's capacity to sustain base flow due to the greater natural capacity to regulate flows. In contrast, scenarios of conversion of forest to pasture generated negative impacts on the river basin, with reduced water availability and increased flood risks. These results can improve water planning and management in this basin, as it is one of the most important regions for public water supply in Paraíba.